CS56 Energy Code Feasibility Study in Revere, Massachusetts
Energy code feasibility study for a 144-unit Multifamily High-rise in Massachusetts. Compares multiple design paths. Recommended: Path C - Ductless Mini-Split + HPWH. View full study.
- Study Type
- Energy Code Feasibility Study
- State
- Massachusetts
- Units
- 144
- Building Type
- Multifamily High-rise
- Fuel Type
- All-Electric
- Recommended Path
- Path C - Ductless Mini-Split + HPWH
Goal
To find the most cost-effective compliance path, this report isolates energy code related costs from total construction. We use real bid data from vendors & clients to create a reliable framework for aligning incentives and design, with all recommendations confirmed by detailed energy modeling.
Project
- Revere, MA 02151
- 144 Units | 85,019 sqft
- 110-story | Multifamily new construction over a parking podium
- All-Electric | Stretch Code | HERS ≤ 45 | ENERGY STAR MFNC v1.2
Overview
Read This: This report compares different ways you can build the project and meet energy code, looking at both cost and incentives, with the ultimate goal as finding the most affordable path.
- The overview outlines the key differences between each of the paths we show in this report and why we recommend the one we picked over the others.
- The recommended design section is where we share the requirements and incentives for the path we think is best based on affordability.
- The path comparison section shows the detailed requirements and incentives for each path we compared, basically showing our work if you want to dig in.
Path Summaries
Path C - Ductless Mini-Split + HPWH (Recommended): HERS/ERI path with ENERGY STAR MFNC v1.2 certification. Uses ductless mini-split heat pumps, single-zone on studios and multi-split on one- and two-bedroom units (SEER2 24.0 to 25.8 / HSPF2 10.0 to 16.2), paired with a heat pump water heater located in the conditioned corridor. Removing the ground loop and all in-unit ductwork drops first cost well below the two water-source paths while keeping double-pane glazing (U-0.25 / SHGC 0.25). All unit types pass with a comfortable margin. Path C also holds the strongest incentive position, as the only path carrying both an induction cooktop and a heat pump water heater. Recommended because it delivers the lowest net cost, the best cost per HERS point, and the simplest mechanical scope.
Path B - Water-Source Heat Pump + HPWH (Great Alternative): HERS/ERI path with ENERGY STAR MFNC v1.2 certification. Uses a ducted water-source heat pump on a shared ground loop with a heat pump water heater, on the same double-pane envelope as Path C. The water-source system carries the ground loop and in-unit ductwork as added first cost, but delivers stable seasonal efficiency from a constant-temperature loop and a concealed, centrally maintained system. All unit types pass with the widest margin of the three paths. A strong alternative for a developer who prefers a ducted, concealed system over wall-mounted indoor heads.
Path A - Water-Source Heat Pump + Electric-Resistance Tank: HERS/ERI path with ENERGY STAR MFNC v1.2 certification. Pairs the same ducted water-source heat pump as Path B with an electric-resistance storage water heater, offset by the most aggressive envelope of the three: triple-pane glazing (U-0.18 / SHGC 0.20) and a wall that adds an R-23 cavity batt behind the continuous insulation. The premium envelope is what carries the electric-resistance water heater to a passing score. Not recommended, as it reaches the same target as Path B at a higher first cost; it is included to show the envelope-heavy route for a developer set on a simple resistance water heater.
Code Path
Permit / Certificate of Occupancy Requirements
High Rise Buildings
Recommended Design
This section outlines the design requirements, product recommendations, and incentives for the design that we believe will be the most affordable path to meeting energy code.
Recommended Design - Incentives
Incentives Available: $338,400 - $554,400
MassSave Multifamily High Rise Program Energy Star Tier ($252,000) (Program Breakdown): You get this rebate for having your building(s) certified for the Energy Star MFNC v1.2 program. This requires pre-approval via an application to be submitted before construction starts. This rebate comes in the form of a check within 4 months of certification documentation being provided to MassSave, typically this is 4 months after construction is complete.
DOER Alternative Energy Credits (Program Breakdown) ($0 - $216,000): This rebate is received for installing APS eligible air source heat pumps (click here for the list). There is an extensive process to get this incentive. It comes in the form of a check approximately 6-12 months after the heat pumps are installed and fully operational.
IMPORTANT: Although an estimate is provided, this incentive can vary widely typically between $300-1,500 per heat pump. It's based on expected kWh usage of the system as well as the market value of the alternative energy credits when sold.
Wi-Fi Connected Thermostat Adder ($14,400): A MassSave market transformation adder of $100 per unit for installing a Wi-Fi connected thermostat in each dwelling unit.
In-Unit Heat Pump Water Heater Adder ($36,000): A MassSave market transformation adder of $250 per unit for installing a heat-pump water heater in each dwelling unit.
Induction Cooktop Adder ($36,000): A MassSave market transformation adder of $250 per unit for installing an induction cooktop in each dwelling unit.
Recommended Design - Units
| Item | Detailed Specifications |
|---|---|
| Exterior Walls | Steel studs at 16 in. OC; R-12.6 continuous insulation. |
| Slab | N/A |
| Floor Over Garage | 6 in. concrete podium deck over unconditioned parking; R-30 continuous insulation at the underside. |
| Rim Joists | N/A |
| Roof | Flat roof; R-40 continuous insulation; sealed unvented assembly. |
| Windows | Double-pane low-E; U-0.25; SHGC 0.25. |
| Doors | Opaque: U-0.17. |
| Air Sealing | ≤0.30 CFM50 per sqft of shell area, blower-door tested (Air sealing protocol) (Backup Air Sealing) |
| HVAC | Ductless mini-split air-source cold-climate heat pump; SEER2 24.0 - 25.8 / HSPF2 10.0 - 16.2; ENERGY STAR; R-454B refrigerant. (1BR Product Rec) (2BR Product Rec) (Studio Product Rec) |
| Ductwork | N/A |
| Duct Sealing | N/A |
| HVAC Grading | N/A |
| Mechanical Ventilation | Centralized ERV; sized per ASHRAE 62.2; 80% recovery efficiency. Studio: 25 CFM 1BR: 35 CFM 2BR: 55 CFM (Product Rec) |
| Local Mechanical Exhaust | Bathroom(s): ≥ 50 CFM intermittent & ≤ 3.0 sones OR ≥ 20 CFM continuous & ≤ 2.0 sones. Kitchen(s): ≥ 100 CFM intermittent & ≤ 3.0 sones OR continuous, ≥ 5 ACH. Both: Exhaust directly outdoors, ENERGY STAR certified, utilize ERV. |
| Thermostats | Wi-Fi connected programmable thermostat; one per heat-pump zone; ENERGY STAR certified. (Product Rec) |
| DHW | Heat-pump water heater; UEF 3.5; 50 gal; located in a conditioned corridor. (Product Rec) |
| DHW Piping | Supply piping insulated to R-3; Max DHW pipe run length: Studio: 27.5 ft 1BR: 29.8 ft 2BR: 36.5 ft |
| Water Fixtures | WaterSense: lavatory ≤1.2 GPM; shower ≤2.0 GPM; kitchen ≤2.2 GPM; toilet ≤1.28 GPF. |
| Refrigerator | ENERGY STAR certified; 550 kWh/yr. (Product Rec) |
| Dishwasher | ENERGY STAR certified; 240 kWh/yr; standard tier. (Product Rec) |
| Clothes Washer | ENERGY STAR certified, front-load; IMEF 2.76; 136 kWh/yr. (Product Rec) |
| Clothes Dryer | Electric, vented; standard; CEF 3.93. (Product Rec) |
| Stove / Oven | Electric induction cooktop with convection oven. (Product Rec) |
| Lighting | 100% LED lighting, interior and exterior. |
| Solar Ready | Designated Solar Zone: Reserve a contiguous area equal to at least 40% of the total horizontal roof area (after excluding skylights, occupied decks, vegetated areas, and fire setbacks). Contiguity & Obstructions: The zone must be free of all obstructions (pipes, vents, HVAC units) and maintain a minimum width of 5 feet. Structural Capacity: Roof structures within this zone must be engineered to support a future collateral dead load of 5 PSF. Orientation (Sloped Roofs): For roofs with a pitch of 4:12 or greater, the zone must be oriented between 110° and 270° of true north. Electrical Infrastructure: Provide identified conduit pathways from the roof to the electrical service and reserve a labeled space for a dual-pole circuit breaker in the main panel or common space service. |
| EV Ready | Requirement: Provide EV Ready infrastructure for at least 20% of total parking. Provide a branch circuit and termination for the required spaces (up to 20% total), rated for a system capacity of at least 6.2 kVA per space. |
| HPWH Ready | 240V circuit and condensate drain provided for the heat-pump water heater. |
| Paperwork & Modeling | HERS/ERI energy model; ENERGY STAR MFNC v1.2 certification; IECC compliance checklists; MassSave incentive documentation. |
| Testing & Verification | Unit blower-door test; mechanical ventilation balancing; pre-drywall + final inspection; RESNET sampling plan. |
| Embodied Carbon Credit | Not applicable; HERS 45 is met without the embodied-carbon credit. |
Recommended Design - Common Areas
| Item | Detailed Specifications |
|---|---|
| Exterior Walls | Steel-framed: R-12.6 continuous mineral-wool insulation (matches the residential envelope); meets the 225 CMR 23 commercial prescriptive assembly U-factor for CZ5 |
| Below-Grade Walls | R-10 continuous insulation on conditioned below-grade walls |
| Slab | Unheated slab-on-grade per 225 CMR 23; R-10 perimeter insulation 24 in deep at any heated common-area slab |
| Rim Joists | Continuous air barrier and insulation maintained at all floor-band transitions |
| Roof | R-40 continuous insulation above deck, unvented (matches the residential envelope) |
| Windows | Fixed glazing U-0.36; operable glazing U-0.43; SHGC per 225 CMR 23 commercial fenestration table, CZ5 |
| Doors | Opaque entrance door U-0.37; glazed entrance door U-0.60 |
| Air Sealing | Continuous air barrier across the common-area thermal envelope; tested per the applicable commercial air-barrier provisions |
| HVAC | All-electric. Common-area spaces conditioned by heat pumps at minimum efficiency per 225 CMR 23 / ASHRAE 90.1; sized per ACCA Manual procedures |
| Duct Sealing | Common-area ductwork sealed and leakage-tested per 225 CMR 23 |
| Mechanical Ventilation | Outdoor-air ventilation per ASHRAE 62.1 by space type (corridors, lobby, fitness, community room, laundry, mail room); energy recovery where required by code; demand-controlled ventilation on high-occupancy spaces |
| Local Mechanical Exhaust | ASHRAE 62.1 exhaust rates for common-area restrooms, trash rooms, and mechanical rooms; ducted directly outdoors |
| Thermostats | Programmable thermostats with automatic setback on all common-area zones |
| DHW | Point-of-use electric water heating at common-area restroom lavatories |
| DHW Piping | Hot water piping insulated by pipe diameter per 225 CMR 23 |
| Water Fixtures | WaterSense flow rates: lavatory, shower, kitchen, and code flush volumes for toilets and urinals |
| Lighting | 100% LED; interior lighting power density within 225 CMR 23 / IECC C405 limits by space type (corridor, lobby, fitness, community room, laundry, stair, mechanical, storage) |
| Lighting Controls | Occupancy / vacancy sensors, daylight-responsive controls, and automatic time switches by space type per 225 CMR 23 / IECC C405 |
| Solar Ready | Solar-ready roof zone and electrical infrastructure per the applicable code |
| EV Ready | EV-ready circuits at common-area / resident parking per the applicable code |
| Paperwork & Modeling | COMcheck report; ASHRAE 62.1 ventilation calculations; lighting power density calculations |
| Testing & Verification | Mechanical ventilation balancing; lighting controls commissioning; common-area inspections |
Exterior Wall Assembly (Recommended Design)
Roof (Recommended Design)
Floor Over Garage (Recommended Design)
Path Comparison
This section shows the detailed requirements and incentives for each path we compared, basically showing our work of how we determined the recommended path is the most affordable way of meeting energy code compliance.
Path Comparison - Incentives
Incentives Available (HPWH Paths): $302,400 - $518,400
MassSave Multifamily High Rise Program Energy Star Tier ($252,000) (Program Breakdown): You get this rebate for having your building(s) certified for the Energy Star MFNC v1.2 program. This requires pre-approval via an application to be submitted before construction starts. This rebate comes in the form of a check within 4 months of certification documentation being provided to MassSave, typically this is 4 months after construction is complete.
DOER Alternative Energy Credits (Program Breakdown) ($0 - $216,000): This rebate is received for installing APS eligible air source heat pumps (click here for the list). There is an extensive process to get this incentive. It comes in the form of a check approximately 6-12 months after the heat pumps are installed and fully operational.
IMPORTANT: Although an estimate is provided, this incentive can vary widely typically between $300-1,500 per heat pump. It's based on expected kWh usage of the system as well as the market value of the alternative energy credits when sold.
Wi-Fi Connected Thermostat Adder ($14,400): A MassSave market transformation adder of $100 per unit for installing a Wi-Fi connected thermostat in each dwelling unit.
In-Unit Heat Pump Water Heater Adder ($36,000): A MassSave market transformation adder of $250 per unit for installing a heat-pump water heater in each dwelling unit.
Incentives Available (WSHP & ER Tank): $302,400 - $518,400
MassSave Multifamily High Rise Program Energy Star Tier ($252,000) (Program Breakdown): You get this rebate for having your building(s) certified for the Energy Star MFNC v1.2 program. This requires pre-approval via an application to be submitted before construction starts. This rebate comes in the form of a check within 4 months of certification documentation being provided to MassSave, typically this is 4 months after construction is complete.
DOER Alternative Energy Credits (Program Breakdown) ($0 - $216,000): This rebate is received for installing APS eligible air source heat pumps (click here for the list). There is an extensive process to get this incentive. It comes in the form of a check approximately 6-12 months after the heat pumps are installed and fully operational.
IMPORTANT: Although an estimate is provided, this incentive can vary widely typically between $300-1,500 per heat pump. It's based on expected kWh usage of the system as well as the market value of the alternative energy credits when sold.
Wi-Fi Connected Thermostat Adder ($14,400): A MassSave market transformation adder of $100 per unit for installing a Wi-Fi connected thermostat in each dwelling unit.
Induction Cooktop Adder ($36,000): A MassSave market transformation adder of $250 per unit for installing an induction cooktop in each dwelling unit.
Path Comparison - Net Cost Summary
| Path | Total Cost $/sf | Total Incentives $/sf | Net $/sf | OpEx Factor | Worst HERS |
|---|---|---|---|---|---|
| WSHP & ER Tank | $66.45 | $3.55 | $62.90 | 0.97 | 43 |
| WSHP & HPWH | $61.20 | $3.55 | $57.65 | 0.98 | 42 |
| Mini-Split & HPWH | $48.60 | $3.97 | $44.63 | 0.98 | 43 |
Path Comparison - Envelope
| Item | Path | Detailed Specifications | Cost $/sf | Incentive $/sf | Net $/sf | OpEx Factor |
|---|---|---|---|---|---|---|
| Exterior Walls | WSHP & ER Tank | Steel studs at 16 in. OC; R-23 cavity insulation & R-12.6 continuous insulation. | $14.10 | $0.00 | $14.10 | 0.85 |
| WSHP & HPWH | Steel studs at 16 in. OC; R-12.6 continuous insulation. | $10.40 | $0.00 | $10.40 | 0.85 | |
| Mini-Split & HPWH | Same as Path B. | $10.40 | $0.00 | $10.40 | 0.85 | |
| Slab | WSHP & ER Tank | N/A | $0.00 | $0.00 | $0.00 | 1.00 |
| WSHP & HPWH | N/A | $0.00 | $0.00 | $0.00 | 1.00 | |
| Mini-Split & HPWH | N/A | $0.00 | $0.00 | $0.00 | 1.00 | |
| Floor Over Garage | WSHP & ER Tank | 6 in. concrete podium deck over unconditioned parking; R-30 continuous insulation at the underside. | $2.95 | $0.00 | $2.95 | 0.85 |
| WSHP & HPWH | Same as Path A. | $2.95 | $0.00 | $2.95 | 0.85 | |
| Mini-Split & HPWH | Same as Path A. | $2.95 | $0.00 | $2.95 | 0.85 | |
| Rim Joists | WSHP & ER Tank | N/A | $0.00 | $0.00 | $0.00 | 1.00 |
| WSHP & HPWH | N/A | $0.00 | $0.00 | $0.00 | 1.00 | |
| Mini-Split & HPWH | N/A | $0.00 | $0.00 | $0.00 | 1.00 | |
| Roof | WSHP & ER Tank | Flat roof; R-30 continuous insulation; sealed unvented assembly. | $4.20 | $0.00 | $4.20 | 0.85 |
| WSHP & HPWH | Flat roof; R-40 continuous insulation; sealed unvented assembly. | $5.35 | $0.00 | $5.35 | 0.85 | |
| Mini-Split & HPWH | Same as Path B. | $5.35 | $0.00 | $5.35 | 0.85 | |
| Windows | WSHP & ER Tank | Triple-pane low-E; U-0.18; SHGC 0.20. | $9.80 | $0.00 | $9.80 | 0.90 |
| WSHP & HPWH | Double-pane low-E; U-0.25; SHGC 0.25. | $6.50 | $0.00 | $6.50 | 0.90 | |
| Mini-Split & HPWH | Same as Path B. | $6.50 | $0.00 | $6.50 | 0.90 | |
| Doors | WSHP & ER Tank | Opaque: R-4.75. | $0.45 | $0.00 | $0.45 | 0.95 |
| WSHP & HPWH | Same as Path A. | $0.45 | $0.00 | $0.45 | 0.95 | |
| Mini-Split & HPWH | Same as Path A. | $0.45 | $0.00 | $0.45 | 0.95 | |
| Air Sealing | WSHP & ER Tank | ≤0.30 CFM50 per sqft of shell area, blower-door tested (Air sealing protocol) (Backup Air Sealing) | $1.05 | $0.00 | $1.05 | 0.90 |
| WSHP & HPWH | Same as Path A. | $1.05 | $0.00 | $1.05 | 0.90 | |
| Mini-Split & HPWH | Same as Path A. | $1.05 | $0.00 | $1.05 | 0.90 |
Path Comparison - Mechanical
| Item | Path | Detailed Specifications | Cost $/sf | Incentive $/sf | Net $/sf | OpEx Factor |
|---|---|---|---|---|---|---|
| HVAC | WSHP & ER Tank | Ducted water-source heat pump on a shared loop; COP 3.3 - 3.5 / EER 17.3 - 18.5; all-electric; R-454B refrigerant. (Product Rec) | $17.50 | $0.00 | $17.50 | 1.10 |
| WSHP & HPWH | Same as Path A. | $17.50 | $0.00 | $17.50 | 1.10 | |
| Mini-Split & HPWH | Ductless mini-split air-source cold-climate heat pump; SEER2 24.0 - 25.8 / HSPF2 10.0 - 16.2; ENERGY STAR; R-454B refrigerant. (1BR Product Rec) (2BR Product Rec) (Studio Product Rec) | $8.40 | $0.00 | $8.40 | 1.10 | |
| Ductwork | WSHP & ER Tank | Insulated supply and return ducts, R-6, located entirely within conditioned space. | $3.20 | $0.00 | $3.20 | 1.05 |
| WSHP & HPWH | Same as Path A. | $3.20 | $0.00 | $3.20 | 1.05 | |
| Mini-Split & HPWH | N/A | $0.00 | $0.00 | $0.00 | 1.00 | |
| Duct Sealing | WSHP & ER Tank | Total duct leakage test to greater of 8 CFM25 per 100 sqft CFA or 80 CFM25 to outside (duct sealing protocol). | $0.35 | $0.00 | $0.35 | 1.00 |
| WSHP & HPWH | Same as Path A. | $0.35 | $0.00 | $0.35 | 1.00 | |
| Mini-Split & HPWH | N/A | $0.00 | $0.00 | $0.00 | 1.00 | |
| HVAC Grading | WSHP & ER Tank | N/A | $0.00 | $0.00 | $0.00 | 1.00 |
| WSHP & HPWH | N/A | $0.00 | $0.00 | $0.00 | 1.00 | |
| Mini-Split & HPWH | N/A | $0.00 | $0.00 | $0.00 | 1.00 | |
| Mechanical Ventilation | WSHP & ER Tank | Centralized ERV; sized per ASHRAE 62.2; 80% recovery efficiency. Studio: 25 CFM 1BR: 35 CFM 2BR: 55 CFM (Product Rec) | $2.70 | $0.00 | $2.70 | 1.05 |
| WSHP & HPWH | Same as Path A. | $2.70 | $0.00 | $2.70 | 1.05 | |
| Mini-Split & HPWH | Same as Path A. | $2.70 | $0.00 | $2.70 | 1.05 | |
| Local Mechanical Exhaust | WSHP & ER Tank | Bathroom(s): ≥ 50 CFM intermittent & ≤ 3.0 sones OR ≥ 20 CFM continuous & ≤ 2.0 sones. Kitchen(s): ≥ 100 CFM intermittent & ≤ 3.0 sones OR continuous, ≥ 5 ACH. Both: Exhaust directly outdoors, ENERGY STAR certified, utilize ERV for exhausts. | $0.55 | $0.00 | $0.55 | 1.00 |
| WSHP & HPWH | Same as Path A. | $0.55 | $0.00 | $0.55 | 1.00 | |
| Mini-Split & HPWH | Same as Path A. | $0.55 | $0.00 | $0.55 | 1.00 | |
| Thermostats | WSHP & ER Tank | Wi-Fi connected programmable thermostat; one per heat-pump zone; ENERGY STAR certified. (Product Rec) | $0.30 | $0.17 | $0.13 | 1.00 |
| WSHP & HPWH | Same as Path A. | $0.30 | $0.17 | $0.13 | 1.00 | |
| Mini-Split & HPWH | Same as Path A. | $0.30 | $0.17 | $0.13 | 1.00 |
Path Comparison - Plumbing & Appliances
| Item | Path | Detailed Specifications | Cost $/sf | Incentive $/sf | Net $/sf | OpEx Factor |
|---|---|---|---|---|---|---|
| DHW | WSHP & ER Tank | Electric-resistance storage water heater; UEF 0.93; 50 gal; located in conditioned space. (Product Rec) | $1.20 | $0.00 | $1.20 | 0.90 |
| WSHP & HPWH | Heat-pump water heater; UEF 3.5; 50 gal; located in a conditioned corridor. (Product Rec) | $2.85 | $0.42 | $2.43 | 1.20 | |
| Mini-Split & HPWH | Same as Path B. | $2.85 | $0.42 | $2.43 | 1.20 | |
| DHW Piping | WSHP & ER Tank | Supply piping insulated to R-3; Max DHW pipe run length: Studio: 27.5 ft 1BR: 29.8 ft 2BR: 36.5 ft | $0.60 | $0.00 | $0.60 | 0.95 |
| WSHP & HPWH | Same as Path A. | $0.60 | $0.00 | $0.60 | 0.95 | |
| Mini-Split & HPWH | Same as Path A. | $0.60 | $0.00 | $0.60 | 0.95 | |
| Water Fixtures | WSHP & ER Tank | WaterSense: lavatory ≤1.2 GPM; shower ≤2.0 GPM; kitchen ≤2.2 GPM; toilet ≤1.28 GPF. | $0.50 | $0.00 | $0.50 | 0.95 |
| WSHP & HPWH | Same as Path A. | $0.50 | $0.00 | $0.50 | 0.95 | |
| Mini-Split & HPWH | Same as Path A. | $0.50 | $0.00 | $0.50 | 0.95 | |
| Refrigerator | WSHP & ER Tank | ENERGY STAR certified; 450 kWh/yr. (Product Rec) | $0.95 | $0.00 | $0.95 | 1.00 |
| WSHP & HPWH | ENERGY STAR certified; 550 kWh/yr. (Product Rec) | $0.85 | $0.00 | $0.85 | 1.00 | |
| Mini-Split & HPWH | Same as Path B. | $0.85 | $0.00 | $0.85 | 1.00 | |
| Dishwasher | WSHP & ER Tank | ENERGY STAR certified; 240 kWh/yr; standard tier. (Product Rec) | $0.55 | $0.00 | $0.55 | 1.00 |
| WSHP & HPWH | Same as Path A. | $0.55 | $0.00 | $0.55 | 1.00 | |
| Mini-Split & HPWH | Same as Path A. | $0.55 | $0.00 | $0.55 | 1.00 | |
| Clothes Washer | WSHP & ER Tank | ENERGY STAR certified, front-load; IMEF 2.92; 90 kWh/yr. (Product Rec) | $0.70 | $0.00 | $0.70 | 1.00 |
| WSHP & HPWH | ENERGY STAR certified, front-load; IMEF 2.76; 136 kWh/yr. (Product Rec) | $0.60 | $0.00 | $0.60 | 1.00 | |
| Mini-Split & HPWH | Same as Path B. | $0.60 | $0.00 | $0.60 | 1.00 | |
| Clothes Dryer | WSHP & ER Tank | Electric, ventless heat-pump; CEF 9.0. (Product Rec) | $0.95 | $0.00 | $0.95 | 1.05 |
| WSHP & HPWH | Electric, vented; standard; CEF 3.93. (Product Rec) | $0.50 | $0.00 | $0.50 | 1.00 | |
| Mini-Split & HPWH | Same as Path B. | $0.50 | $0.00 | $0.50 | 1.00 | |
| Stove / Oven | WSHP & ER Tank | Electric induction cooktop with convection oven. (Product Rec) | $0.80 | $0.42 | $0.38 | 1.00 |
| WSHP & HPWH | Electric; radiant or coil cooktop. (Product Rec) | $0.55 | $0.00 | $0.55 | 1.00 | |
| Mini-Split & HPWH | Electric induction cooktop with convection oven. (Product Rec) | $0.80 | $0.42 | $0.38 | 1.00 |
Path Comparison - Electrical
| Item | Path | Detailed Specifications | Cost $/sf | Incentive $/sf | Net $/sf | OpEx Factor |
|---|---|---|---|---|---|---|
| Lighting | WSHP & ER Tank | 100% LED lighting, interior and exterior. | $0.45 | $0.00 | $0.45 | 0.85 |
| WSHP & HPWH | Same as Path A. | $0.45 | $0.00 | $0.45 | 0.85 | |
| Mini-Split & HPWH | Same as Path A. | $0.45 | $0.00 | $0.45 | 0.85 | |
| Solar Ready | WSHP & ER Tank | Designated Solar Zone: Reserve a contiguous area equal to at least 40% of the total horizontal roof area. Contiguity: Zone free of obstructions, minimum 5 ft wide. Structural Capacity: 5 PSF collateral dead load. Electrical Infrastructure: Conduit pathways and reserved breaker space. | $0.35 | $0.00 | $0.35 | 1.00 |
| WSHP & HPWH | Same as Path A. | $0.35 | $0.00 | $0.35 | 1.00 | |
| Mini-Split & HPWH | Same as Path A. | $0.35 | $0.00 | $0.35 | 1.00 | |
| EV Ready | WSHP & ER Tank | EV-Ready parking per R404.4; dedicated 240V branch circuit terminating within reach of the space. | $0.55 | $0.00 | $0.55 | 1.00 |
| WSHP & HPWH | Same as Path A. | $0.55 | $0.00 | $0.55 | 1.00 | |
| Mini-Split & HPWH | Same as Path A. | $0.55 | $0.00 | $0.55 | 1.00 | |
| HPWH Ready | WSHP & ER Tank | N/A | $0.15 | $0.00 | $0.15 | 1.00 |
| WSHP & HPWH | N/A | $0.00 | $0.00 | $0.00 | 1.00 | |
| Mini-Split & HPWH | N/A | $0.00 | $0.00 | $0.00 | 1.00 |
Path Comparison - Soft Costs
| Item | Path | Detailed Specifications | Cost $/sf | Incentive $/sf | Net $/sf | OpEx Factor |
|---|---|---|---|---|---|---|
| Paperwork & Modeling | WSHP & ER Tank | HERS/ERI energy model; ENERGY STAR MFNC v1.2 certification; IECC compliance checklists; MassSave incentive documentation. | $0.70 | $2.96 | -$2.26 | 1.00 |
| WSHP & HPWH | Same as Path A. | $0.70 | $2.96 | -$2.26 | 1.00 | |
| Mini-Split & HPWH | Same as Path A. | $0.70 | $2.96 | -$2.26 | 1.00 | |
| Testing & Verification | WSHP & ER Tank | Unit blower-door test; Total duct leakage test; mechanical ventilation balancing; pre-drywall + final inspection; RESNET sampling plan. | $0.85 | $0.00 | $0.85 | 1.00 |
| WSHP & HPWH | Same as Path A. | $0.85 | $0.00 | $0.85 | 1.00 | |
| Mini-Split & HPWH | Unit blower-door test; mechanical ventilation balancing; pre-drywall + final inspection; RESNET sampling plan. | $0.65 | $0.00 | $0.65 | 1.00 | |
| Embodied Carbon Credit | WSHP & ER Tank | N/A | $0.00 | $0.00 | $0.00 | 1.00 |
| WSHP & HPWH | Same as Path A. | $0.00 | $0.00 | $0.00 | 1.00 | |
| Mini-Split & HPWH | Same as Path A. | $0.00 | $0.00 | $0.00 | 1.00 |
Additional Design Considerations Not Represented In This Study
R-30 continuous roof on Paths B & C: Building-wide envelope UA at the v1.2 Residential-Option backstop climbs from 100% to 101% of the ceiling at R-30. Held at R-40, which keeps B/C at 100% Residential / 93% Commercial Option.
R-15 (or higher) continuous-insulation wall on Paths B & C: At R-15+ the wall assembly (≈U-0.052) clears the v1.2 Residential-Option backstop outright. Held at R-12.6 ci because the Commercial-Option backstop election clears the spec at the thinner board, and R-12.6 matches a real Rockwool ComfortBoard 80 (3 in).
R-23 cavity batt + R-12.6 ci wall on Paths B & C (matching Path A): Path A needs the hybrid wall to carry the electric-resistance tank; the HPWH on B/C already carries them to HERS 42 / 43, so the cavity batt produces no compliance benefit. Held at ci-only.
Triple-pane glazing (U-0.18 / SHGC 0.20) on Paths B & C: Path A relies on triple-pane to compensate for the electric-resistance tank (HERS 43). Paths B & C reach HERS 42 / 43 on double-pane (U-0.25) because the HPWH absorbs the water-heating load. Held at double-pane.
Heat-pump ventless dryer (CEF 9.0) on Paths B & C: Path A retains the HP dryer to support the resistance tank. Paths B & C reach HERS 42 / 43 with the standard vented dryer (CEF 3.93) at 3- and 2-point buffers; the HP dryer earns no compliance margin on the HPWH paths.
Induction cooktop on Path B: Paths A and C use induction Path B reaches HERS 42 (3-point buffer) with a standard radiant cooktop; induction does not change the compliance position. Held at standard radiant.
MA embodied-carbon (concrete-GWP) compliance path with the relaxed HERS 48 target on Path A: Path A is all-electric and clears the standard HERS 45 target directly (HERS 43, 2-point buffer); the relaxed embodied-carbon target was not required. Held at HERS 45.
ENERGY STAR MFNC v1.2 Residential-Option thermal backstop on Paths B & C: The R-12.6 ci-only steel-stud wall puts the building's total envelope UA at 100% of the Residential-Option ceiling — razor-thin even with the R-40 roof and double-pane credited: The Commercial-Option (2021 IECC C402.1.4 Group R) drops B/C to 92-94%. Held with the Commercial-Option election recommended.
DHW pipe runs at 1/3 of the ANSI reference: All three paths pass with buffer at the 1/2 setting (HERS 43 / 42 / 43 vs the 45 target); the tighter 1/3 run was not required. Held at 1/2.